html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/1142#issuecomment-266032884,https://api.github.com/repos/pydata/xarray/issues/1142,266032884,MDEyOklzc3VlQ29tbWVudDI2NjAzMjg4NA==,19403647,2016-12-09T14:56:35Z,2016-12-09T14:56:35Z,NONE,"Hi, I have taken another approach for using nd window over several dimensions of  xarray objects to perform filtering and tapering, based on `scipy.ndimage`, `scipy.signal ` and ` dask.map_overlap`.  @shoyer @jhamman it is somewhat similar to what I have presented during the aospy meeting. It also refers to the issue #819.

For the moment, I have something that works like this :
```
shape = (50, 30, 40)
dims = ('x', 'y', 'z')
dummy_array = xr.DataArray(np.random.random(shape), dims=dims)
# Define and set a window object
w = dummy_array.window
w.set(n={'x':24, 'y':24}, cutoff={'x':0.01, 'y':0.01}, window='hanning')
```
where ` n` is the filter order (i.e. the size), `cutoff` is the cutoff frequency, `window` is any window name that can be found in the `scipy.signal.windows` collection. 

Then the filtering can be perform using the `w.convolve()` method, which build a dask graph for the convolution product.

I also want to add a tapering method 'w.taper()' which would be useful for spectral analysis. For multi-tapering, it should also generate an object with an additional dimension corresponding to the number of windows. To do that, I first need to handle the window building using dask.

Let me know if you are interesting in this approach. For the moment, I have planned to upload a github project for signal processing tools in the framework of [pangeo-data](https://pangeo-data.github.io/). It sould be online by the end of December and I will happy to have feedback on it. I am not sure it falls into the xarray framework and it may need a dedicated project, but I might be wrong.  
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,192248351